Ca2+ transient, Mg2+, and pH measurements in the cardiac cycle by 19F NMR.
AUTOR(ES)
Kirschenlohr, H L
RESUMO
19F NMR indicators have been used to measure the free cytosolic cation concentrations ([Mn+]i, where M is the atomic symbol and n is the value of the charge) of Ca2+, H+, and Mg2+ in perfused ferret hearts. The [Ca2+]i transient, cytosolic pH (pHi), and [Mg2+]i have also been followed at 16 phases in the cardiac cycle in hearts paced at 1.25 Hz at 30 degrees C. The initial [Ca2+]i rose rapidly after a 50-ms delay, was maximal at greater than 1.5 microM after 150 ms, and declined thereafter to the initial concentration. In contrast, no significant changes in pHi (pH 7.03 +/- 0.08) or [Mg2+]i (1.2 +/- 0.1 mM) were detected in the cycle. A decrease in developed pressure when the [Ca2+]i indicator (but not the pHi or [Mg2+]i indicator) was loaded into hearts was substantially reversed by the addition of 50 microM ZnCl2 to the perfusion medium. The Zn2+ was taken up into the myoplasm and displaced Ca2+ bound to the indicator, a symmetrically substituted difluoro derivative of 1,2-bis(o-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid (5FBAPTA), as evidenced by the appearance of the Zn-5FBAPTA resonance. The decrease in developed pressure caused by 5FBAPTA, therefore, may be due to its Ca2+ buffering effect on the myoplasm. By coloading hearts with the [Ca2+]i and pHi indicators, simultaneous measurement of several [Mn+]i was demonstrated, which should provide a useful addition to the methods available to monitor cardiac function and pharmacology.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=282653Documentos Relacionados
- Regulation of intracellular pH by human peripheral blood lymphocytes as measured by 19F NMR.
- Lead increases free Ca2+ concentration in cultured osteoblastic bone cells: simultaneous detection of intracellular free Pb2+ by 19F NMR.
- Intracellular pH in human skeletal muscle by 1H NMR.
- Intracellular calcium measurements by 19F NMR of fluorine-labeled chelators.
- 19F NMR measurements of the rotational mobility of proteins in vivo.